AV flow restrictors
A shunt comprising a flexible tube having a first, and a second end, and a central opening, having a first diameter that extends from the first end to the second end. The shunt also includes one or more restrictor bands having a second diameter around the flexible tube. The one or more restrictor bands are located between the first end and the second end of the flexible tube and the second diameter is less than the first diameter such that the restrictor band forms a restriction. The restrictor band is expandable between a first position and a second position. The restrictor band may have fracturable sections configured to fracture in responds to pressure thereby increasing a diameter of the one or more restrictor bands to a diameter greater than the second diameter. The one or more restrictor bands may comprise restrictor bands of at least two different inner diameters.
The field of the invention relates generally to venous grafts and in particular to flow restrictors created to modify the flow dynamics.
2. BACKGROUND OF THE INVENTIONThere are currently more than 400,000 patients in the United States with end-stage renal disease (ESRD) and many times more throughout the world. Patients with ESRD have lost their normal kidney function and as a result require dialysis to substitute the function of the kidney cleansing the blood.
The challenge with providing hemodialysis is maintaining access to large volumes of blood when our bodies constantly fight medical attempts to keep dialysis access available. Currently there are three ways to provide hemodialysis: dialysis catheters, arterial venous fistulas, and arterial venous grafts. All current methods are however limited, providing access for only short periods of time. This requires patients to have repeated invasive procedures for survival. Additionally, with AV shunt devices to provide dialysis there is blood shunted away from the hand and continuous loss of cardiac output. This can lead to unwanted medical consequences. To overcome the drawbacks of the prior art, the disclosed design extends the life of the dialysis graft and well as decreasing the loss of blood to the extremity while also maintaining the cardiac output, thus prolonging the lives of patients.
SUMMARYArterial-Venous fistulas and grafts termed AV shunts are the most effective means to provide large volume blood access for hemodialysis patients. Patency rates however are relatively low as both means of AV shunts occlude primarily because normal vein stenosis occurs at the output of the graft as a result of high pressure, pulsation and flow rates. An additional limitation of current AV shunts is the stealing of blood from the artery that would normally feed the distal portion of the extremity, such as the finger. This blood is shunted through the AV fistula back to the heart, thus bypassing the lower portion of the extremity. This creates two issues, the first is distal extremity ischemia that often results in finger loss through amputation and the constant loss of cardiac output making the heart work much harder, continuously, than it normally would without a shunt. One proposed means and method to surgically treat this is to create a vascular band around the fistula or graft creating a surgical flow restrictor. Another method described in prior Batiste designs is a manufactured flow restrictor with the body of the graft or fistula. Other Batiste patents describe several such devices including preformed restrictor, balloon restrictors and restrictors using cellular materials among several others. U.S. Pat. No. 8,715,218 issued to Batiste entitled Self Adjusting Venous Equalizing Graft and Endothelial Lining Therefore issued on May 6, 2014 is incorporated by reference in its entirety therein.
This invention provides an innovative means to create a flow restrictor within an AV shunt that can be modified if hemodynamics or patient clinical condition changes. The design utilizes a mechanical band that functions to selectively and controllably restrict the inner diameter of the AV shunt. The innovative band may contain several different properties as described including several embodiments including a pliable design that once stretched with a balloon stays expanded completely eliminating the stenosis, a fracturable band which breaks at predetermined sites in order to release the flow restriction narrowing and eliminating the narrowing, and an elastic design which reforms the original flow restrictor configuration once the balloon therapy is removed. The expandable, fracturable and elastic flow restrictors can be placed prior to shunt surgical placement or via percutaneous endovascular placement as described herein.
Disclosed herein is a shunt having a flexible tube which has a first and second end, and a central opening with a first diameter extending from the first to the second end. The flexible tube has one or more restrictor bands which have a second diameter around the flexible tube. The restrictor band is located between the first and second end of the flexible tube, and the second diameter is less than the flexible tube's first diameter.
In one embodiment the shunt described above is an arterial venous shunt (AV shunt) which may be configured to have a restrictor band that expands between a first and a second position. The restrictor band may include sections that are configured to fracture (i.e., fracturable sections) in response to outward pressure thereby increasing a diameter of the one or more restrictor bands to a diameter greater than the second diameter. In one or more embodiments, the one or more restrictor bands in the AV shunt have at least two different inner diameters.
The AV shunt's tube length has an inlet end, an outlet end, and a central opening which extends from the inlet to the outlet ends such that central opening has a first diameter. In this embodiment, at least one band extends around a portion of the tube length and is located between the ends. The bands create a reduced diameter section of a second diameter that is adjustable from the second diameter, which is less than the first diameter to a third diameter which is greater than the second diameter. The AV shunt's third diameter may be the same as the first diameter.
The AV shunt's band may be further expandable from the third diameter to a fourth diameter, the fourth diameter being greater than the third diameter. In some embodiments, the band also has sections which are configured to fracture in response to outward pressure thereby increasing the band from the second diameter to the third diameter and may further contain two or more restrictor bands of at least two different inner diameters.
In one configuration, the tube functioning as an AV shunt, has a central opening with a first diameter extending from both the inlet and outlet ends. In one embodiment, the at least one band, has a second diameter which extends around the tube and is located between the inlet end and the outlet end, that creates a reduced diameter section in the tube such that the band is configured to expand in response to outward pressure and increase its diameter to adjust from the second diameter to a third diameter and then maintain the third diameter after the outward pressure is removed from the band. The amount of increase in diameter of the band is responsive to an amount of outward pressure. The band may be manufactured from elastic material which does not return to its original shape when expanded. In this embodiment, the inlet end of the AV shunt is configured to be connected to an artery, while the outlet end is configured to be connected to a vein. In other embodiments, multiple bands made from a fractionable material having differing diameters are arranged on one tube and consist of two sets of opposing mirrored sets of bands.
Other systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description.
In one or more embodiments the invention utilizes a band to create external pressure on elements in order to narrow the inner lumen of a dialysis shunt thereby creating a stenosis that acts as a flow restrictor. The restricted flow then creates the perfect hemodynamic conditions within the shunt helping to eliminate shunt failure and improve flow to the extremities while decreasing cardiac output. As shown in
Once created or deployed various clinical situations may dictate modification of the restrictor whether permanent or temporary. The modification may include the diameter of the restriction or the length of the restricted section. Thus, the design anticipates the need to alter the restrictor once placed. The restrictor, bands 10 may be altered with various materials depending on the clinical situation and hence the restrictors bands may be expandable, fracturable or elastic. In some embodiments, the restrictor bands 10 return, or can be manipulated to return, to a narrower diameter after being expanded.
As shown in
In a second embodiment, shown in
A third embodiment of the material design is that of a resistor band 14 made of elastic materials. As shown in
In one embodiment, the shunt is equipped with two or more fracturable restrictor bands such that one or more of the restrictor bands have a different diameter. In a basic embodiment, the first restrictor band has an inner diameter that is less than the inner diameter of the second restrictor band. Both are located around the outer surface of the shunt. In use, the shunt is paced in a patient which establishes a restriction or stenosis in the shunt thereby reducing blood flow. If, over time, it is determined that the restriction is too great, then a balloon may be directed through a blood vessel to the shunt and filled with gas or liquid to increase the diameter of the balloon. The diameter of the balloon may be increased sufficiently to fracture the first restrictor band, while leaving the second restrictor band unaffected. Thus, after fracturing the first restrictor band, the inner diameter of the opening is increased to the diameter of the second restrictor band. If the doctor again determines the blood flow restriction is too great, then a balloon may be inserted inside the second restrictor to fracture the second structure thereby again increasing the inner diameter of the shunt. This may occur with more than two restrictor bands to create additional degrees of control over the restriction size.
In operation, a balloon (not shown) or other expansion device, may be inserted into the tube 100 and expanded sufficiently to fracture or otherwise expand the first band 810 thereby changing the diameter of the stenosis from the first diameter to the second diameter. If that stenosis is too small, then the process can be repeated at a later time to break the second band 814. This process may repeat to provide adjustability in the amount of narrowing in the stenosis including no narrowing by breaking all bands.
While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible that are within the scope of this invention. In addition, the various features, elements, and embodiments described herein may be claimed or combined in any combination or arrangement.
Claims
1. A dialysis stent with an expandable restriction, the dialysis stent being configured for use with an arterial venous (AV) fistula or graft in a manner wherein the AV fistula or graft connects an artery of a patient to a vein of the patient, and configured for treating renal disease in the patient, comprising:
- a shunt tube having an inlet end and an outlet end and configured to be deployed within the AV fistula or graft, the shunt tube having a central opening which extends from the inlet end to the outlet end such that the central opening has a first diameter; and
- at least one elastic band configured to narrow the central opening of the shunt tube and thereby create a stenosis in the shunt tube that acts as a flow restrictor for allowing the shunt tube to elastically shunt blood flow from an extremity of the patient, the at least one elastic band extending around a portion of the shunt tube and located between the inlet end and the outlet end without folding of the at least one elastic band, the at least one elastic band creating a reduced diameter section of a second diameter in the shunt tube that is elastically adjustable from the second diameter, which is less than the first diameter, to a third diameter that is greater than the second diameter such that the stenosis expands when the shunt tube moves from having the second diameter to having the third diameter, the at least one elastic band exerting radial pressure on the shunt tube toward having the second diameter both when the shunt tube has the second diameter and when the shunt tube has the third diameter, the at least one elastic band configured to elastically adjust from the second diameter to the third diameter responsive to a balloon inflating to expand the at least one elastic band, and from the third diameter back to the second diameter responsive to the balloon subsequently deflating, the at least one elastic band elastically reforming from an expanded state to an original state when adjusting from the third diameter back to the second diameter, the at least one elastic band being made of an elastic material different than a material of the shunt tube in order to create a radially inward pressure on the shunt tube and to allow the shunt tube to have smooth inner and outer surfaces proximate the at least one elastic band.
2. The stent of claim 1, wherein the at least one elastic band that is adjustable from the second diameter is reactive to outward pressure from within the shunt tube toward the at least one elastic band that causes the at least one elastic band to expand, thereby eliminating or increasing a diameter of the restriction to establish the shunt tube at a diameter greater than the second diameter during a clot clearing procedure.
3. The stent of claim 1, wherein the third diameter is the same as the first diameter.
4. The stent of claim 1, wherein the at least one elastic band is expandable from the third diameter to a fourth diameter, the fourth diameter greater than the third diameter.
5. The stent of claim 1, wherein the at least one elastic band has preset fracture points at predetermined sites that are configured to fracture before other locations of the band in order to allow the release of pressure and an associated radial force in response to pressure that expands the band beyond the first diameter thereby increasing the band from the second diameter to the third diameter.
6. The stent of claim 1, wherein the at least one elastic band comprises two or more restrictor bands of at least two different inner diameters, each of which is formed from an elastic material.
7. The stent of claim 1, wherein the at least one elastic band returns to the second diameter after a period of time sufficient to provide time for the shunt tube to have a clot removed therefrom.
8. The stent of claim 1, wherein the shunt tube is configured to adjust from the second diameter to the third diameter without the at least one elastic band being stitched to the shunt tube.
9. The stent of claim 1, wherein the shunt tube is configured to elastically adjust from the third diameter back to the second diameter without an additional medical procedure in a manner wherein the at least one elastic band is a sole force for radially contracting the shunt tube back to the second diameter.
10. The stent of claim 1, wherein the shunt tube and the at least one elastic band each have a middle disposed midway between the inlet and outlet ends of the shunt tube.
11. The stent of claim 1, wherein, when the shunt tube adjusts from the second diameter to the third diameter, the shunt tube radially expands outwardly.
12. The stent of claim 1, wherein the shunt tube is configured to elastically adjust from the third diameter back to the second diameter without an additional medical procedure in a manner wherein the at least one elastic band is a sole force for radially contracting the shunt tube back to the second diameter, wherein the shunt tube is configured to adjust from the second diameter without the at least one elastic band being stitched to the shunt tube, wherein the shunt tube and the at least one elastic band each have a middle disposed midway between the inlet and outlet ends of the shunt tube, and wherein, when the shunt tube is configured to adjust from the second diameter to the third diameter, the shunt tube radially expands outwardly.
13. The stent according to claim 6, wherein the two or more restrictor bands each have a different corresponding width.
14. The stent according to claim 6, wherein the two or more restrictor bands each have a different corresponding thickness.
15. A dialysis stent with an expandable restriction, the dialysis stent being configured for use with an arterial venous (AV) fistula or graft in a manner wherein the AV fistula or graft connects an artery of a patient to a vein of the patient, and configured for treating renal disease in the patient, comprising:
- a shunt tube having an inlet end and an outlet end and configured to be deployed within the AV fistula or graft, the shunt tube having a central opening which extends from the inlet end to the outlet end such that the central opening has a first diameter; and
- at least one elastic restrictor configured to narrow the central opening of the shunt tube and thereby create a stenosis in the shunt tube that acts as a flow restrictor for allowing the shunt tube to elastically shunt blood flow from an extremity of the patient, the at least one elastic restrictor extending around a portion of the shunt tube and located between the inlet end and the outlet end without folding of the at least one elastic restrictor, the at least one elastic restrictor creating a reduced diameter section of a second diameter in the shunt tube that is elastically adjustable from the second diameter, which is less than the first diameter, to a third diameter that is greater than the second diameter such that the stenosis expands when the shunt tube moves from having the second diameter to having the third diameter, the at least one elastic restrictor exerting radial pressure on the shunt tube toward having the second diameter both when the shunt tube has the second diameter and when the shunt tube has the third diameter.
16. The stent according to claim 1, wherein the at least one elastic restrictor is configured to narrow the central opening of the shunt tube and thereby create the stenosis in the shunt tube such that the stenosis is disposed midway between the inlet end of the shunt tube and the outlet end of the shunt tube.
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Type: Grant
Filed: May 25, 2023
Date of Patent: Jan 6, 2026
Patent Publication Number: 20230293800
Inventor: Stan Batiste (Granite Bay, CA)
Primary Examiner: Rebecca E Eisenberg
Assistant Examiner: Alessandro R Del Priore
Application Number: 18/202,010
International Classification: A61M 1/36 (20060101);